This invention relates to a seal which is removably attached by adhesive means to a cover of a can or a like container in such a manner so as to tightly cover openings therein.
Various prior devices have been known for this purpose. One prior device providing easy means of a can opening comprises a finger-catch means rigidly secured to the cover of a can having a series of perforations along the periphery of the cover. In that case, the finger-catch means is securely attached to the cover near the peripheral perforated line; pulling this means detaches the cover therewith from the can body.
According to another prior device, two parallel lines of perforations are provided along the peripheral upper end portion of the can body. In that case, the can is opened by winding the perforated portion by separate winding means to sever the can body into two parts.
According to still further prior art, a heat-contracted sealing material is used to cover a bottle cork to seal the bottle tightly. In this case, the cork is removed from the bottle by detaching the sealing material therefrom.
However, these prior arts present disadvantages since in the first two cases, choice of material for making the can body or cover is very restricted and the manufacturing process becomes complicated, thus unavoidably slowing down the manufacturing speed of cans. In the last case, processing steps after filling the contents into bottles must be increased.
In order to eliminate these disadvantages, another prior invention provides an airtight film material of a strong nature adapted to cover an opening provided in the cover. This may have improvements over all the earlier arts since it permits an easier manner of manufacturing cans and provides for fewer treatments after filling the contents into cans. In this case, a can can be easily opened simply by detaching the film material therefrom. However, the very easiness with which the can is opened does harm to the sealing function.
The present invention provides an improvement over all the prior arts to overcome the disadvantages as hereinafter described.